Emperor Ling of Han (156/157 – 13 May 189), personal name Liu Hong, was the 12th emperor of the Eastern Han dynasty. He was also the last Eastern Han emperor to exercise effective power during his reign. Born the son of a lesser marquis who descended directly from Emperor Zhang (the third Eastern Han emperor), Liu Hong was chosen to be emperor in February 168 around age 12 after the death of his predecessor, Emperor Huan, who had no son to succeed him. He reigned for about 21 years until his death in May 189.

Emperor Ling's reign saw another repetition of corrupt eunuchs dominating the eastern Han central government, as was the case during his predecessor's reign. Zhang Rang, the leader of the eunuch faction (十常侍), managed to dominate the political scene after defeating a faction led by Empress Dowager Dou's father, Dou Wu, and the Confucian scholar-official Chen Fan in October 168. After reaching adulthood, Emperor Ling was not interested in state affairs and preferred to indulge in women and a decadent lifestyle. At the same time, corrupt officials in the Han government levied heavy taxes on the peasants. He exacerbated the situation by introducing a practice of selling political offices for money; this practice severely damaged the Han civil service system and led to widespread corruption. Mounting grievances against the Han government led to the outbreak of the peasant-led Yellow Turban Rebellion in early 184.

Emperor Ling's reign left the Eastern Han dynasty weak and on the verge of collapse. After his death, the Han Empire disintegrated in chaos for the subsequent decades as various regional warlords fought for power and dominance. (See End of the Han dynasty.) The Han dynasty ended in late 220 when Emperor Ling's son, Emperor Xian, abdicated his throne – an event leading to the start of the Three Kingdoms period in China.

Liu Hong was a hereditary marquis – the Marquis of Jiedu Village (解瀆亭侯). In the Han dynasty, a village marquis's marquisate usually comprised only one village or, in rarer cases, two or three villages. He was the third person in his family to hold this title; his father Liu Chang (劉萇) and grandfather Liu Shu (劉淑) were also formerly Marquis of Jiedu Village. His great-grandfather, Liu Kai (劉開), Prince Xiao of Hejian (河間孝王), was the sixth son of Emperor Zhang, the third emperor of the Eastern Han dynasty. His mother, Lady Dong, was Liu Chang's formal spouse.

When Emperor Huan died on 25 January 168 without a son to succeed him, his empress, Empress Dou, became empress dowager, and she examined the genealogy of the imperial clan to choose a candidate to be the next emperor. For reasons unknown, her assistant Liu Shu (劉儵) recommended Liu Hong, the Marquis of Jiedu Village. After consulting with her father Dou Wu and the Confucian scholar-official Chen Fan, Empress Dowager Dou installed a 12-year-old Liu Hong on the throne on 17 February 168, and continued ruling on his behalf as regent. The newly enthroned Emperor Ling bestowed posthumous titles on his grandfather, father and grandmother, honouring them as emperors and an empress respectively. His mother, Lady Dong, did not become empress dowager and instead received the title of an Honoured Lady.

Dou Wu and Chen Fan, who became the most important officials in the central government (being the General-in-Chief and Grand Tutor respectively), sought to purge the eunuch faction. Later in 168, they even proposed to exterminate all the powerful eunuchs, a proposal that Empress Dowager Dou rejected. However, word of the plot was leaked, and the eunuchs, after kidnapping the empress dowager and taking the young emperor into custody (after persuading him that it was for his own protection) arrested and executed Chen Fan. Dou Wu resisted but was eventually defeated and forced to commit suicide. The Dou clan was slaughtered. The powerful eunuchs, led by Cao Jie (曹節) and Wang Fu (王甫), became the most powerful individuals in the central government.

After the destruction of the Dou clan, in 169, Emperor Ling promoted his mother to the position of empress dowager, though he continued honouring Empress Dowager Dou, now under house arrest, as empress dowager as well. Members of the Dong clan began to enter government, but did not have substantial influence. Later that year, the eunuchs persuaded Emperor Ling that the "partisans" (i.e., Confucian officials and those who supported them) were plotting against him, and a large number of partisans were arrested and killed; the others had their civil liberties stripped completely, in an event historically known as the second Disaster of Partisan Prohibitions.

Empress Dowager Dou died in 172. Despite suggestions by eunuchs to have her only buried as an imperial consort and not be honoured as Emperor Huan's wife, Emperor Ling had her buried with full honours befitting an empress dowager in Emperor Huan's mausoleum. In the aftermaths of her death, a vandal wrote on the palace gate: "All that is under the heaven is in upheaval. Cao and Wang murdered the empress dowager. The key officials only know how to be officials and had nothing faithful to say."